$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
10.23
\begin{equation} \begin{gathered}\label{equation:universal-property-of-image} \xymatrix@R =50pt@C=50pt{ X \ar [d]^{q} \ar [dr]^{f} & \\ Y_0 \ar [r]^-{i_0} & Y } \end{gathered} \end{equation}